| Land resources are the material basis for human survival and development,and an important carrier of economic and social development.With the continuous development of society and urbanization,the way of using land resources is constantly changed by human beings,and the unreasonable use and development of land has caused adverse effects on land ecological security,which has triggered a series of ecological security problems and restricted the sustainable development of the region,and the contradiction between human and land needs to be solved urgently.Therefore,it is important to analyze and study the land use changes in the region,analyze the land ecological safety situation in the region by evaluating the land ecological safety,and make predictions and zoning control,so as to propose management measures for the future development in the region and better promote the sustainable development of the region.In this paper,using RS and GIS technology,based on the Google Earth Engine(GEE)cloud platform,Landsat series images were selected as the data source,and the three phases of land use data in the study area in 2000,2015 and 2020 were obtained through the method of random forest,and their changes were analyzed;based on the he PSR model was used to select indicators to construct the land ecological safety evaluation index system,and the entropy weighting method and hierarchical analysis were used to determine the weights,and the comprehensive index method was adopted to determine the land ecological safety index,which was divided into five levels: insecure,less secure,critically secure,more secure and secure,to evaluate the land ecological safety of the three phases,and to carry out change analysis from two scales: time and space,and through the grey prediction The model predicts the land ecological security of each township in 2025 and 2030,and proposes zoning control measures for Junan County based on the prediction results and evaluation results.The main findings of the study are as follows:(1)Based on the Google Earth Engine cloud platform computing platform,this paper adopts the random forest classification method for land use classification,and the overall accuracy reaches more than 95%,and the kappa coefficient reaches more than 0.88,so the classification results are good.According to the classification results,the land use type is mainly arable land,and the greatest degree of land use change is construction land;the annual rate of land use change and the degree of land use increase year by year,and the land use transfer mainly shows the transfer of arable land to construction land,which has a certain impact on land ecological security,and the land use transfer is mainly concentrated in Lingquan Town,Crossroad Street,Pingshang Town,Zhu Lu Town,Tuanlin Town and Zhuanggang Township(2)The land ecological security index of Jounan County in 2010,2015 and 2020 is0.499,0.536 and 0.541 respectively,showing an increasing trend of change.In terms of the area of the land security grades,it is mainly less secure and critically secure.In terms of changes in the area of each grade,the degree of change between insecure and secure is relatively small,with the greatest decrease in the rate of insecure areas at 23.72% and the greatest increase in the rate of land area that is critically secure at 22.87%;the lowest land ecological security indices in 2010,2015 and 2020 are in Shilianzi Town,Tuanlin Town and Fangqian Town,respectively,and the highest land ecological security indices are in Floodplain The towns with the highest land ecological safety index are Floodplain Town,Feibin Town and Zhu Lu Town;from the viewpoint of changes in the land ecological safety index of each township,the towns that are increasing include Zhuanggang Town,Ping Shang Town and Zhu Lu Town,while the towns that are increasing and then decreasing are Xianggou Town,Subian Town,Banquan Town,Fangqian Town,Lingquan Town,Crossroad Street,Feibin Town,Daokou Town,Floodplain Town,Shilianzi Town,Wenshui Town and Dadian Town,and the township that is decreasing and then increasing in land safety index is Tuanlin Town.(3)The overall spatial distribution of land ecological safety in 2010,2015 and 2020 in Junan County shows the characteristics that the western plain area is better than the eastern hilly area,and the land ecological safety level in the central area is more complicated to change during the study period;there are 25 mapping units of land ecological safety level changes in Junan County from 2010 to 2020,and the mapping units that are transformed to other land ecological safety levels are 20 The area of 75,191.18 hm~2,accounting for 42.947%of the total area,and the largest area of more insecure-critically secure shifts is 42,984.87hm~2,accounting for 24.551% of the total area,mainly concentrated in Zhu Lu Town,Ping Shang Town,Zhuang Gang Town,Feast Bin Town,Ling Quan Town and Ban Quan Town;the area and proportion of stable types in the mapping of land ecological security pattern changes is the largest,with a The area and proportion of the pre-stable type are the smallest,with Zhuanggang town as the base and extending to the northeast;the area and proportion of the full-period change type are second only to the stable type,distributed in the north and south of Feixingbin town;the late stable type is distributed in the west in a "human" shape with Feixingbin town as the base.(4)The distribution in 2025 and 2030 is characterised by the eastern port area being better than the central and western areas,which is also related to the policy of developing colour chemical,modern agriculture and cultural tourism industries in the port area.Based on the change in rank of each township in Jounan County from 2020 to 2030,the county is divided into an improvement zone,a stability zone and a regression zone.The enhancement zone will maintain the current development and requirements in the future development,and adopt technological innovation and reform and industrial transformation to promote the further development of the enhancement zone;the stability zone can be prevented by means of fallow or crop rotation to prevent pollution from the opposite source;the regression zone can play a regulatory role through enterprises and the government,with the government taking the lead and relevant enterprises and parts jointly working together to solve the soil pollution problem. |
